How to Use CoreMIDI for Music Production on an iPad or iPhone

how to use coremidiI’m currently obsessed with the idea that the iPad, and other iOS devices like the iPhone or iPod Touch, represent a serious step forward for music production on a budget. Software synthesizers, touch-friendly DAWs and drum samples from the summer of love are all vastly more affordable than the hardware they aim to replace, and the growing number of available apps makes iOS the world’s most portable production platform.

Apple added CoreMIDI to iOS 4.2 and since then app developers have been implementing MIDI functionality into their apps. This means you can use your iOS device as both a MIDI controller and with MIDI input devices for physical, tactile key response. CoreMIDI can also be used with apps or multiple iOS devices for a studio-like automated setup.

Excited? Here’s what you need to know about how to use CoreMIDI.

Knowing MIDI, Knowing You 

MIDI stands for Musical Instrument Digital Interface and was introduced in 1983 when artists like The Human League and Culture Club dominated the charts, armed with Roland drum machines and Casio keyboards. Our musical tastes have come a long way since then but MIDI hasn’t changed an awful lot aside from being more widespread in its application.

how to use coremidi

MIDI doesn’t carry sound but instead a signal which denotes pitch, note, volume and other parameters. This means you can use the same MIDI patterns on a huge range of instruments, simply by changing the destination device. Apple’s CoreMIDI works in the same way, accepting and sending signals to and from compatible hardware.

This functionality has been in iOS for a long time now, and over the last few years app support has grown tremendously. This goes for apps that support MIDI input (such as keyboards and DJ interfaces) as well as apps designed to drive external MIDI devices which I’ll come to later. When it comes to physical controllers and instruments, there’s only really one thing you need to use MIDI on your iOS device, and that’s an interface.

There are a few interfaces to choose from, with the most basic being Apple’s camera connection kit ($29) which adds a regular USB port to whatever you plug it into. From here you can then use any USB MIDI connection kit like the M-Audio Uno, provided it acts as a generic USB MIDI device. Devices that require drivers – i.e. manufacturer-enhanced MIDI connectors – will not work unless they’re put into generic USB mode.

A potentially more cost-effective option would be to purchase a dedicated MIDI accessory such as the MIDI Mobilizer II from Line 6 (not the original MIDI Mobilizer, which is not CoreMIDI compatible) or the iRig MIDI from IK Multimedia. Which option to go for depends on whether you currently own a USB MIDI interface or not, and whether you foresee yourself using the camera connector for its initial intended purpose.

Note: Some USB devices connected using the camera connector require more power than the iPad is willing to provide. While simple USB keyboards like the Akai LPK25 will work flawlessly, larger and hungrier inputs will require a powered USB hub in order to work. If you’re thinking of using a full-sized, externally powered keyboard then this won’t be an issue seeing as it will be mains-powered.

CoreMIDI & Apps

In addition to being a hardware interface using physical cables, CoreMIDI is capable of acting as a software interface and wirelessly too. Wireless MIDI usually takes the form of an app-to-app connection, and enables two or more iOS devices to communicate provided they share the same network. Latency might be an issue for routers that still use older wireless standards, and unfortunately Bluetooth connection is not possible.

One such app that makes use of CoreMIDI for wireless control is Funkbox, which can receive and send signals like clock speed, transport and note triggers to and from controllers and drum machines. Synthetic Bits, the developers of Funkbox, have also developed what is easily one of the simplest and best MIDI controllers for iOS called Little MIDI Machine, available for free. It allows you to sequence MIDI hardware, iOS apps and other iOS devices wirelessly and with all components working together, it’s a very advanced system as you can see from the video below.

MIDI uses numbered channels to send its various signals, and in order to trigger a specific instrument you will need to make sure that the channels match up, and this goes for both physical hardware connections and app or wireless connections too.. So to trigger a synth like Sunrizer which is listening to channel 10, you would need to set the output of your step sequencer (in this instance Little MIDI) to channel 10 also. It’s a simple system to grip once you’ve played with a set of apps or devices, and it’s an excellent way of finely-tuning a sequence before trying it out on a variety of instruments.

Another often useful feature is MIDI Learn. Apps that support MIDI Learn allow you to assign various physical controls like volume or filter cutoff to sliders and knobs on physical controllers. In order to use MIDI Learn you will first need to activate the learning interface in the app you are using, then tap the function before assigning it to a knob or slider by moving it. Sunrizer supports this for a huge number of variables, and it also works for other functions like triggering an arpeggiator or holding notes.

So Where Do I Start? 

If you’ve never played with MIDI before and would like to see the potential first-hand you should download Little MIDI from the App Store as well as a cheap instrument like miniSynth 2 ($0.99) or Apple’s own GarageBand ($4.99) each of which support CoreMIDI. Both of these apps should be able to talk to your sequencer with default routing. Before building your sequence ensure you have turned on BG Audio on the synth (it’s under the FX panel) or Run in Background under GarageBand settings and mute the internal Little MIDI Machine piano note in the settings.

how to use coremidi

You can now sequence miniSynth 2 or GarageBand with Little MIDI Machine by adjusting pitch, velocity and various other triggers. To really master MIDI work your way through the brief but detailed Little MIDI Machine manual which provides a crash-course in sequencing a synth. You’ll probably drop the manual once you’ve figured much of it out! If you’re sick of switching between apps and are lucky enough to own an iPad and an iPhone you can even use CoreMIDI over Wi-Fi to sequence a synth on one device and play it on the other. Magic.